Coin tester having a pair of induction coils

ABSTRACT

A coin tester comprises a pair of oscillators respectively connected to a pair of self-induction coils with a coin track extending through the fields of the coils, the oscillators being connected in a logic circuit so that the oscillation of one of the oscillators temporarily ceases when an acceptable coin passes along the coin track and the oscillations of both temporarily cease or are uninterrupted when another object passes along the coin track.

United States Patent Mario Meloni Mini/BE, Switzerland 795,608

Jan. 31, 1969 Feb. 9, 1971 Autelca AG Gumligen, Switzerland Feb. 5, 1968 Switzerland lnventor Appl. No. Filed Patented Assignee Priority COIN TESTER HAVING A PAIR OF INDUCTION COILS 5 Claims, 1 Drawing Fig.

US. Cl. 194/100 Int. Cl G071 3/02 FieldoiSearch 194/100, 101

[5 6] References Cited UNITED STATES PATENTS 3,059,749 10/ l 962 Zinke 194/100 3,317,016 5/1967 Turillon 194/100 Primary Examiner-Stanley H. Tollberg Attorney-Brady, OBoyle and Gates ABSTRACT: A coin tester comprises a pair of oscillators respectively connected to a pair of self-induction coils with a coin track extending through the fields of the coils, the oscillators being connected in a logic circuit so that the oscillation of one of the oscillators temporarily ceases when an acceptable coin passesalong the coin track and the oscillations of both temporarily cease or are uninterrupted when another object passes along the coin track.

IPATENTEUFEH emu 3561.580

1 A I 82M '25 31 IL "I" l t 2s D N L C 4 F2. LT E Inventor:

MAR/o MELON/ BY m 024,4 M22 A T TOR NE Y5 COIN TESTER HAVING A PAIR OF INDUCTION COILS In my copending U.S. Pat. application No. 698,926, filed Jan. 18th, 1968, now U. S. Pat. No. 3,481,443 issued Dec. 2, 1969, I have disclosed a coin tester, in particular for automatic vending machines and coin operated telephones, the coin track of which for the metal objects in coin form to be tested, extends through the field of at least one self-induction coil which is part of the oscillating circuit of an oscillator so con structed that its oscillations temporarily cease or not cease due to the effect of a metal object passing through the coin track depending on the electrical and magnetic properties of said metal object, acceptance or nonacceptance of the metal object depending on whether the oscillations cease.

In the coin tester disclosed in my aforesaid copending application, acceptance or nonacceptance of the metal object depends on whether its effect on the oscillator exceeds or does not reach a limit set by the construction of said oscillator.

It is an object of the present invention to improve the coin tester according to my aforesaid copending application so that only metal objects whose effect on the oscillator is defined between two predetermined limits, can be accepted as acceptable coins.

According to the invention this is achieved in that the coin track successively extends through the fields of at least one pair of self-induction coils which are respectively connected to a pair of oscillators and the oscillators are so constructed that the effect of an acceptable coin passing through the coin track causes temporary cessation of the oscillations of only one of the oscillators while the effect of another object passing through the coin track causes temporary cessation of the oscillation of both oscillators or the continuance of both oscillator oscillations. y j

Y To this end one of the oscillators can be so constructed that the effect of an acceptable coin is just sufficient to cause interruption of its oscillations and the other oscillator can be so constructed that the effect of an acceptable coin is not sufficient to temporarily interrupt its oscillations.

Further objects, features and advantages of the present invention will be clear to those skilled in the art from the following description thereof taken in conjunction with the accompanying drawings, which diagrammatically illustrate a coin tester according to the present invention.

In the illustrated coin tester the coin track 2 formed in a body I extends through the field of aself-induction coil 3 and with a core 4 thereafter through the field of a self-induction coil 23 having a core 24.

The coil 3 is part of the oscillator circuit consisting of the circuit 20 which comprises an oscillator and a rectifier following thereon. The coil 23 is part of the oscillator circuit of a circuit 25 comprising an oscillator and a rectifier for rectifying the oscillations of said oscillator. If the oscillations of the oscillator of circuit 20 or 25 respectively cease temporarily, the rectifier of the aforementioned circuit will supply a pulse to conductor A or to conductor C respectively. The feedback of each of the two oscillators is so adjusted that an acceptable coin passing through the coin track 2 is just sufficient to cause the oscillations of the oscillator of circuit 20 to cease temporarily but insufiicient to also cause the oscillations of the oscillator of circuit 25 to cease.

A logic circuit 26 to 31 supplies at its output F a coin acceptance pulse only if a pulse which occurs on conductor A is not followed by any pulse on conductor C within a predetermined time. This predetermined time is longer than the time required by an object 2a in coin form which drops through the coin track 2 in order to pass successively through the fields of both self-induction coils 3 and 23 and its is shorter than the interval of time during which successively inserted objects in coin form traverse through the coin track. If none of the rectifiers of the circuits 20 and 25 supply a pulse or if both rectifiers supply pulses within the aforementioned period of time, no coin acceptance signal willoccur at the output F of the logic circuit.

The logic circuit comprises an OR gate 26, a multivibrator 27, a univibrator 28, a differential circuit 29, an inverter 30 and an AND gate 31. The multivibrator 27 is associated with resetting means 32 to reset the aforementioned multivibrator after each operation and after delay period has elapsed since operation, said delay period being longer than the period of time which an object dropping through the coin track requires for traversing the fields of both coils 3 and 23 and shorter than the time interval in which successively inserted objects in coin form traverse through the coin track.

The time constant of the univibrator 28 is subject to the same condition with the exception that the aforementioned time constant is shorter than the above-mentioned delay period of the resetting means 32. The multivibrator 27 and the univibrator 28 are together supplied with the output pulse of the OR gate 26 to whose inputs one each of the conductors A and C extend. The univibrator 28 is followed in succession by the differential circuit 29 and the inverter 30 whose output E extends to one of the inputs of the AND gate 31. The other input of the AND gate 31 is connected to the output of the multivibrator 27 which carries a voltage after the multivibrator is operated from its quiescent state. The output of the OR gate 31 is the output F of the logic circuit.

Since the feedback of the oscillators of circuit 20 and 25 is adjusted as described hereinbefore, a coin traversing through the coin track 2 produces only one pulse on the conductor A. Said pulse passes via the OR gate 26 to reach the multivibrator 27 as well the univibrator 28. The multivibrator 27 thereupon supplies a voltage to one of the inputs of the AND gate 31. At the beginning of the output pulse of the univibrator 28 the differential circuit 29 will supply a pulse which cannot render the AND gate 31 conductive because it was previously inverted in the inverter 30. At the end of the output pulse of the univibrator 28 the differential circuit 29 supplies a pulse of opposite polarity which is inverted in the inverter 30 and thereupon has a polarity suitable for rendering the AND gate 31 conductive. Since the delay period of the resetting means 32 is longer than the time constant of the univibrator 28, the output voltage of the multivibrator 27 will still be effective at the AND gate 31 if the aforementioned pulse which was inverted in the inverter 30 reaches the AND gate 31 so that said pulse renders said AND gate 31 conductive and a coin acceptance pulse occurs at the output F. I

Since the feedback of the oscillators 20 and 25 is adjusted as described above, an object, not acceptable as an acceptable coin and traversing through the coin track 2, supplies a pulse either to the conductor A and thereafter to the conductor C or does not supply a pulse to either of these conductors.

If a pulse occurs on conductor C after a pulse on conductor A, the multivibrator 27 will be operated twice in succession so that it does not supply any voltage to the AND gate 31 if at the end of the pulse supplied by the univibrator 28 the pulse inverted in the inverter 30 reaches the AND gate 31 so that no coin acceptance signal occurs at the output F.

If no pulse occurs on either of the conductors A and C the logic circuit 27 to 32 remains in its quiescent state so that no coin acceptance signal occurs at the output F.

Since a time, longer than the time required by an object dropping through the coin track for trav rsing the fields of coils 3 and 23 shall have elapsed after an o ration of the multivibrator 27, and since such time is short r than the time interval in which two successively inserted bject traverse the coin track 2, the resetting means 32 will return the multivibrator into its initial state. The coin tester is then ready for testing the next object which drops through the coin track.

To test coins of different denominations it is possible for the coin tester described hereinabove to be'yprovided for each coin denomination with one system of the kind heretofore described with reference to the coin, the coil pairs of the individual systems being disposed successively along the coin track and the logic circuit of each system supplying a coin acceptance signal onlyif an acceptable coin of the corresponding denomination traverses the coin track.

Each coin acceptance signal may set a branch inorder to guide the object whichhas traversed through the coin track either into a track for acceptable coins or into a track for other objects. It is however also'possible for all objects inserted for operation of an automatic vending machine or coin operated telephone to be guided into one container and for all objects to be encashed incommon or ,to be rejected in common depending on the result of the test.

lclaim:

l. A coin tester comprising at least one pair of self-induction coils, a pair of oscillators respectively connected to said self-induction coils, means defining a cointrack extending through the fields of said self-induction coils, and means for causing the oscillation of only one of said'oscillators to temporarily cease in response to passage of an acceptable coin along said coin track and for causing the oscillations of both of said oscillators to temporarily cease or for causing the oscillations of both of-said oscillators to be uninterrupted in response to passage of another object alongsaid coin track.

2. A coin tester as claimed in claim 1, further comprising rectifiers, each of which'is adapted to rectify the oscillations of one of said oscillators and supply a pulse in the event of temporary cessation of said oscillations, and a logic circuit adapted to transmit a coin acceptance pulse only if only one of said rectifiers supplies a pulse to said. logic circuit within a predetermined time which is at least equalto the time required by an object, to pass through.said;coin;track fortraversing the fields-0f saidself-induction coils and'is, smaller than the time interval between successively inserted coins.

3. A coin tester as claimed inclaim 2; whereinsaid logic circuit comprises aunivibrator a time constant within the limits of said time, a=multivibrator, means for! resettingsaidmultivibrator, after operation thereof, with adelay which is .also within said time limits but whichiexceeds the time constant'of said univibrator, differentialcircuit means for differentiating the output voltage of said'univibrator', an inverter'for. the output voltageof said differential circuit means, and an-AND gate, said AND gate having two inputs, and one ofsa'id outputs being connectedto the output of saidmultivibrator and: the

other being connected to the outputof the invertenandhaving an output which delivers the coin acceptance signal,

4. A coin tester as claimedin claim 3, further comprising an OR gate, means for connecting-each of thc two inputs of said OR gate tothe output of one of. said rectifiers, and means forconnecting the output of i the 0K to the input of. said multivibrator and of said univibraton 5. A coin tester as c'laimedinpclaimlgwherein'one pairof said self-induction coils and of said oscillators is provided foreach of'aplurality of coin-denominations, pairs vof self-inductor coils being disposed. at a distance fromeach other along saidcoin track. I 

1. A coin tester comprising at least one pair of self-induction coils, a pair of oscillators respectively connected to said selfinduction coils, means defining a coin track extending through the fields of said self-induction coils, and means for causing the oscillation of only one of said oscillators to temporarily cease in response to passage of an acceptable coin along said coin track and for causing the oscillations of both of said oscillators to temporarily cease or for causing the oscillations of both of said oscillators to be uninterrupted in response to passage of another object along said coin track.
 2. A coin tester as claimed in claim 1, further comprising rectifiers, each of which is adapted to rectify the oscillations of one of said oscillators and supply a pulse in the event of temporary cessation of said oscillations, and a logic circuit adapted to transmit a coin acceptance pulse only if only one of said rectifiers supplies a pulse to said logic circuit within a predetermined time which is at least equal to the time required by an object to pass through said coin track for traversing the fields of said self-induction coils and is smaller than the time interval between successively inserted coins.
 3. A coin tester as claimed in claim 2, wherein said logic circuit comprises a univibrator a time constant within the limits of said time, a multivibrator, means for resetting said multivibrator, after operation thereof, with a delay which is also within said time limits but which exceeds the time constant of said univibrator, differential circuit means for differentiating the output voltage of said univibrator, an inverter for the output voltage of said differential circuit means, and an AND gate, said AND gate having two inputs, and one of said outputs being connected to the output of said multivibrator and the other being connected to the output of the inverter and having an output which delivers the coin acceptance signal.
 4. A coin tester as claimed in claim 3, fUrther comprising an OR gate, means for connecting each of the two inputs of said OR gate to the output of one of said rectifiers, and means for connecting the output of the OR to the input of said multivibrator and of said univibrator.
 5. A coin tester as claimed in claim 1, wherein one pair of said self-induction coils and of said oscillators is provided for each of a plurality of coin denominations, pairs of self-inductor coils being disposed at a distance from each other along said coin track. 